The short answer is that a criminal defense attorney may be able to challenge the swearch warrant and argue for a suppression of the evidence that was seized as a result of the warrant (meaning that the prosecutor may not have much of a case against you). This is a very fact specific analysis and you need to discuss it with a local criminal defense attorney if you are going to get anywhere with it.
It depends. First, the copy of the warrant you were given may not have been signed but the original was. It may have been a telephonic search warrant. All search warrants and the "return" on that warrant are supposed to be filed with the Clerk of Courts. Check there.
You need a local attorney to look into this for you. If you can't afford one, your should be talking with the Public Defender's office.
This is not legal advice, which requires a personal connection and far more facts.